<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- <script src="./测试.js"></script> -->
</head>

<body>
    <script>
        function foo() {
            console.log(this.a);
        }
        var a = 10;
        foo();
    </script>


</body>

</html>